Ethanol consumption has been part of the human condition for centuries, yet excessive amounts can lead to serious medical problems. Measuring ethanol directly is a challenge in that it has a short half-life in bodily fluids, but newer blood and urine markers show promise in detecting this substance over longer periods of time, writes Matthew H. Slawson, PhD, and Kamisha L. Johnson-Davis, PhD, in the June issue of Clinical and Forensic Toxicology News, an AACC/College of American Pathologists (CAP) educational newsletter for toxicology laboratories and individuals with an interest in toxicology.

The authors describe how the human body absorbs, distributes, metabolizes and eliminates ethanol, and what factors lead to ethanol toxicity, such as chronic alcohol abuse.

“Ethanol toxicity is largely related to its mechanism of action and its metabolism. Ethanol is a small molecule that can pass through the blood-brain barrier to exert its effects. Ethanol use can increase fatty acid synthesis and lead to fatty deposits in the liver,” the authors explain.

Ethanol is also referred to as ethyl alcohol. Consistently abusing this substance can lead to liver damage, as well as nutritional and neurologic disorders. “Use of ethanol concurrent with other central nervous system depressants can exacerbate the effects of both, leading to severe adverse reactions and even death,” according to the article.

Slawson and Johnson-Davis describe the methods for measuring ethanol through breath analysis and in blood. “A major disadvantage of measuring ethanol directly is its short half-life of 2 to 14 hours,” the authors emphasized. Some of the newer markers have shown promise in detecting ethanol consumption days or even weeks later.

One blood marker, phosphatidylethanol (PEth) has shown effectiveness in detecting chronic heavy drinking. “PEth is not detectable in blood after a single administration of ethanol, but forms from chronic or binge use, usually exceeding 50 g. Its half-life is 3 to 5 days, with a window of detection of about 28 days. It is not affected by liver disease,” according to the authors.

Urinary markers ethyl glucuronide and ethyl sulfate have the capacity to detect ethanol up to 7 days after consumption. “These markers can be used in forensic investigations to determine alcohol use days after ingestion

and in abstinence programs in which blood collection is undesirable or impractical,” the authors noted.

None of these markers appear to be affected by the presence of liver disease.

“Markers of Ethanol Use: Blood and Urine Can Both Be Used,” is the lead article in the June issue of CFTN. Read this issue and earn one hour of ACCENT® credit at no charge.

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